Phorometer.



no. 670,923. P

E. T. ALLENl &. E.- H. GRIFFIN;v

' ruonomean.

(Application lsd May 3. 19001) atont'qd Apr. 2, |9'0I.

(llo Model.)

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Fries.

EDMUND T. ALLEN AND EGBERT I'IEVITT GRIFFIN, OF OIIIOAGO, ILLINOIS,ASSIGNORS TO THE L. MANASSE COMPANY, OF SAME PLACE.

PHOROMETER.

SPEGIFLEGATIGN formingpart of Letters Patent No. 670,923, dated April 2,1901.

Application le. May 3, 1900.

To all whom, t may concern.:

Be it known that we, EDMUND T. ALLEN and EGBERT Hnwrrr GRIFFIN, citizensof the United States, residing at Chicago, in the county of Cook andState of Illinois, have invented a certain new and useful Improves mentin Phorometers, of which the following is a specitication.

Our invention relates to instruments for io testing the eyes, and hasfor its object to provide a new and improved instrument for thispurpose.

Our invention is illustrated in the accompanying drawings, wherein-Figure l is a front end View of a construction embodying our invention.Fig. 2 is a section on line t2 2, Fig. l. Fig. 3 is a view showing theimages seen through the eyepieces as they should appear to the normaleye when the device is adjusted for `the vertical muscles. Fig. 4 is asimilar View when the device is adjusted for the horizontal muscles.Fig. 5 is a section on line 5 5, Fig. 1.

Like letters refer to like parts throughout the several figures.

One of the objects of our invention is to provide one instrument bymeans of which a complete test can be made for heterophoriathat is,insufticiency of the muscles of rotation of the eye.

We have shown in the drawings one construction embodying our invention.In this construction we provide a suitable casing A, of any desirablematerial and formed in any suitable shape. This casing is provided witha light passage-way A', which has an admissionopening A2 for theadmission of the light. The light may be taken from any source, eitheran artificial source or the sun or sky. The light passage-way A', asherein shown, consists of a tube extending only part way the length ofthe casing A. This tube is proiled at its inner end with a glass endpiece provided a suitable light deecting or reflecting device B. Thismay consist of a mirror or a prism or any other suitable device. Thedevice B is preferably made adjustable in any desired manner. As hereinshown, said delecting device is pivotally connected with some part ofthe casingA and is provided with In front of the light passage-way A is-Seriai No.15,308. tNo model.)

l, a suitable adjusting device, consisting of one or more adjListing-screws B' and a retractingspring B2. A second light detlectingor reflecting device C is placed at the rear of the casing A and is alsoprovided with a suitable adjusting device, which, as shown, consists ofone or more adjusting-screws O' and the spring O2. The casing is alsoprovided with the two eyeadjustable, so that they may be moved to andfrom each other to adjust to the position of the eyes of the personlookin through them. Any suitable adjusting device may be used. Asherein shown,the eyepieces are provided with projecting lugs G, havingscrew threaded openings. A rod Gr', having a right and left handscrew-thread, engages said lugs, so that when rotated in one directionthe eyepieces will move toward each other and when rotated 7o in theother direction said eyepieces will be separated. Said eyepieces areprovided with overlapping parts G2, which slide upon each other when theparts are adjusted and which prevent the outside light from entering4the 75 casing A. A partition F is provided and is placed between theeyepieces and the light passage-way A', so as to shut off the lightcoming through said passage-way and preventit from passing directly tothe eyepieces. 8o One of the eyepieces-say, for example, the eyepieceD-is provided with a red glass D', and in combination with this glass isused some suitable device or lens for distorting the light, so that onlooking therethrough a long red line or streak is seen. Any suitabledevice for this purpose can be used, and, as herein illustrated, we haveshown a maddoxrod D2, which consists of a round rod with one sideflattened. The eyepiece E is provided 9o with a green glass E', and asuitable device or lens is used with it for doubling the image or deviceseen through the eyepiece. As herein shown, we use the double prisms E2,having the bases placed together. The maddoX-rod and the double prismsare fastened in suitable parts D3 E3, so that they can be movablyattached to the eyepieces D and E, thus permitting them to be rotated,as it were, l

in order that their position may be varied. los Suitable pins D4 E4 areprovided for facilitating this rotation and variation of said parts.

pieces D and E, which are preferably made 6o vIt is of course evidentthat any construction for holding the parts in position may be used.

The casing A may be adjustably mounted in any desired manner. As hereinshown, it is provided with a projecting support H, which works in thestand H', the stand being provided with a pinion which engages a rack onthe support H, the casing being raised or lowered by operating thethumb-screw H2.

We have described in detail a particular construction in order to makeour invention clear; but it is of course evident that the parts may bevaried in many particulars without in any manner departing from thespirit of our invention, and we therefore do not limit ourselves to theconstruction shown.

In operating the device the light passage-r way A is directed toward asuitable source of light. The light then enters the passageway andstrikes the reflecting device B. This reflecting de-vice is suitablyadjusted to throw the light toward the reflecting deviceC. Said latterreflecting device is suitably adjusted to throw the light toward theeyepieces. The person looking through the eyepiece D when the instrumentis properly adjusted will see a red streak, and upon looking through theeyepiece E he will see two green spots. If now the eyepieces areproperly adjusted and a patient whose extrinsic eye-muscles are allnormal looks through them he will see the red streak midway between thetwo green spots. Then the test is being made for the verticle muscles,the lenses of the eyepieces are moved so that the red streak appears ina horizontal position between the two green spots, as shown in Fig. 3.In order to test the horizontal muscles, the lenses are turned while thepatient is looking through said eyepieces. The prism inserted to bringthe red streak midway between the two green spots indicates thecorrection necessary to remedy the defect in the eye-muscles.

It is of course evident that instead of using red and green glass we mayuse any other glass or any other means of producing a contrast of color,so as to prevent any confusion between the images seen through the twoeyepieces.

It is of course desirable that all light eX- cept that entering throughthe light passageway A be excluded, so that the patient looks into aperfectly dark chamber, where the only things to be seen are the redstreak and the green spots.

We claiml. A device for manipulating testing-lenses for use in testingthe eyes, consisting of a case which serves as a dark chamber, having alight-aperture at one end, a passage-way for such light, an adjustablemirror at the opposite end to receive the light, a second adjustablemirror on the same end as the light-receiving aperture, and twolens-receiving eyepieces opposed to and at the opposite end of the casefrom the second adjustable mirror.

2. A device for manipulating testing-lenses .for use in testing theeyes, consisting of a case which serves as a dark chamber, an internaldivision-platewhich divides the case more or less into two compartments,a lightreceiving aperture and an adjustable mirror in one compartment,twoeyepieces and an opposed adjustable mirror at opposite ends of theother compartment, and suitable means for manipulating the lenses in theeyepieces, substantially as described.

EDMUND T. ALLEN. EGBERT HEwITT GRIFFIN.

Witnesses:

DONALD M. CARTER, HoMER L. KRAFT.

